This documentation is not using the current rendering mechanism and is probably outdated. The extension maintainer should switch to the new system. Details on how to use the rendering mechanism can be found here.
The developer-level documentation for the Calendar Base extension is a work in progress. Eventually, the calendar model that other extensions can plug into will be described here. Likewise, the service-based views are easily extensible by third-party extensions so examples for this will be provided as well. In the meantime, a high-level architecture of the Calendar base extension is provided below.